Combination delivery of Adjudin and Doxorubicin via integrating drug conjugation and nanocarrier approaches for the treatment of drug-resistant cancer cells

Abstract

Combination therapy has been regarded as a potent strategy to overcome multidrug resistance (MDR). In this study, we adopt Adjudin (ADD), a mitochondria inhibitor, and Doxorubicin (DOX), a common chemo-drug, to treat drug-resistant cancer cells (MCF-7/ADR) in combination. Given the different physico-chemical properties of ADD and DOX, we develop a novel drug formulation (ADD–DOX (M)) by integrating drug conjugation and nanocarrier approaches to realize the co-delivery of the two drugs. We demonstrate the conjugation of ADD and DOX via formation of an acid-sensitive hydrazone bond, and then the encapsulation of ADD–DOX conjugates by DSPE-PEG₂₀₀₀ micelles with high drug encapsulation efficiency and well-controllable drug loading efficiency. The obtained ADD–DOX (M) micelles are found to be stable under physiological conditions, but can rapidly release drugs within acidic environments. Following cellular experiments confirm that ADD–DOX (M) vehicles can be internalized by MCF-7/ADR cancer cells through an endocytic pathway and exist within the moderate acidic endolysosomes, thus accelerating the hydrolysis of ADD–DOX and the release of free ADD and DOX. As a result, the ADD–DOX (M) formulation exhibits an excellent anti-MDR effect. In summary, we for the first time report the combinational use of ADD and DOX with an effective co-delivery strategy for the treatment of MDR cancer cells.